PVTIME – LONGi, the world’s only photovoltaic enterprise with the capability to manufacture wafer-scale, ultra-thin, flexible tandem cells, has partnered with Soochow University to make a significant breakthrough in next-generation PV technology. Their collaborative research has resulted in a high-efficiency, stable flexible perovskite-silicon tandem solar cell that overcomes key barriers to commercialisation.
Traditional monocrystalline silicon cells are approaching the 29.4% theoretical lab-scale conversion efficiency limit. In contrast, perovskite-silicon tandem structures enable the full utilisation of sunlight across different wavelengths and offer a theoretical efficiency of over 43%. They are widely acknowledged as a transformative next-generation PV technology. Ultra-thin, flexible, silicon-based tandem cells with lightweight, bendable properties could unlock novel applications, including wearable devices and curved, building-integrated photovoltaics.
However, a critical challenge to commercialising such flexible devices has been their inferior stability and lifespan compared to rigid alternatives. Repeated bending and temperature fluctuations often cause interface delamination and failure. To address this issue, research teams from LONGi, led by Li Zhenguo, Xu Xixiang, and He Bo, and from Soochow University, led by Professors Zhang Xiaohong and Liu Jiang, have developed an innovative ‘tight-loose’ dual-buffer layer structure. The loose layer absorbs and dissipates strain energy to reduce mechanical stress, and the dense layer ensures efficient interface charge extraction and stable connectivity. This provides robust protection for the flexible tandem cells.
These ultra-thin, flexible, tandem cells, which are approximately 60 microns thick and were produced using this new technology, have set two world records. They achieved an efficiency of 33.4% at lab scale and 29.8% at full silicon wafer scale, as certified by the U.S. National Renewable Energy Laboratory, with a notable power-to-weight ratio of 1.77W/g.
Industry experts have noted that this breakthrough will elevate China’s photovoltaic industry from ‘efficiency leadership’ to ‘scenario leadership’, thereby contributing Chinese expertise to the global energy transition.
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